Pen lights are small flashlights approximately the size of a pen. They generally include a retaining clip that enables the light to be held within the user's breast pocket in the same fashion as a pen. Many pen lights are sold as disposable items (i.e., the batteries are not replaceable) and these disposable pen lights usually include an arrangement whereby the retaining clip is used as the on-off switch for the light. In one such arrangement, the clip is electrically and mechanically secured to one of the batteries at its upper end. The casing for the light includes a small opening at the lowermost extremity of the clip so that the user can push the bottom of the clip through the opening into engagement with a conductive surface within the casing to close the circuit between the batteries and light. One common construction is shown in U.S. Pat. No. 3,806,724 to Tanner et al.
With such constructions, during storage and transit, a transparent plastic sleeve is placed over the casing beneath the clip so that the clip cannot be pushed into engagement with the conductive foil within the casing. This is done to prevent inadvertent completion of the electrical circuit which might deplete the battery power unintentionally. However, many consumers are unaware of the function served by the plastic sleeves and fail to remove the sleeve before attempting to use the light. On occasion lights containing the sleeve have been returned to retail outlets by dissatisfied customers contending that the product is inoperable.
Moreover, it is relatively costly to manufacture a pen light with the clip construction shown in U.S. Pat. No. 3,806,724 because the retaining clip must be manually inserted into the casing. Furthermore, with that type of construction, in order to maintain the circuit open when the light is not being used and to reduce the likelihood of unintentional switch closure, the lower end of the clip must be separated from the conductive foil (and thus the casing) by a relatively large distance which diminishes its capacity to "clip" the pen light to the user's pocket, an annoying inconvenience to the user.